Impact attenuator system

ABSTRACT

An impact attenuator system includes a hyperelastic member that comprises an energy absorbing material which behaves in a rate-independent hyperelastic manner so that its permanent set is minimized and the material can absorb tremendous amounts of impact energy while remaining fully recoverable.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 10/991,080,filed Nov. 17, 2004, the disclosure of which is hereby incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to an energy absorbing apparatus. Theinvention relates in general to a fully redirective and non-gatingimpact attenuator apparatus.

Many types of energy absorbing devices are positioned along highways andracetracks to prevent vehicles from crashing into stationary structuresand to lessen the injuries to occupants of the vehicle and to lessen theimpact and damage that will occur to the vehicle.

In the past, many of these devices have been rigid structures thatrestrain the vehicle from leaving the highway. One problem is that thevehicle itself is crushed and bears the brunt of the impact. Anotherproblem with rigid barrier is that the vehicle may rebound back onto thehighway and into oncoming traffic. See for example, U.S. Pat. No.3,845,936 to Boedecker, Jr. et al., issued Nov. 5, 1974, which disclosesa rigid barrier composed of aligned barrels.

Other types of barriers include energy absorbing barrier devices thatare placed along highways and raceways. Many types of such barrier havebeen proposed. For example, one type of barrier device uses one-timecollapsible energy absorbing materials that are crushed or broken awayupon impact. These types of devices are damaged or destroyed duringimpact and must be replaced after a single impact which is timeconsuming, expensive and leaves the roadway unprotected during therepair time. See for example, U.S. Pat. No. 3,982,734, to Walker, issuedSep. 28, 1976; U.S. Pat. No. 4,321,989 to Meinzer issued Mar. 30, 1982;U.S. Pat. No. 4,352,484 to Gertz et al., issued Oct. 5, 1982; U.S. Pat.No. 4,815,565 to Sicking et al., issued Mar. 28, 1989; U.S. Pat. No.5,797,592 to Machado, issued Aug. 25, 1998; U.S. Pat. No. 5,851,005 toMuller et al., issued Dec. 22, 1998; U.S. Pat. No. 5,957,435 toBronstad, issued Sep. 28, 1999; U.S. Pat. No. 6,126,144 to Hirsch etal., issued Oct. 3, 2000; U.S Pat. No. 6,409,417 to Muller et al.,issued Jun. 25, 2002; U.S. Pat. No. 6,536,985 to Albritton, issued Mar.25, 2003; US2001/0014254 to Albritton published Aug. 16, 2001;US2002/0090260 Albritton, published Jul. 11, 2002; US2003/0175076A1 toAlbritton, published Sep. 18, 2003; US2003/0234390 to Bronstad,published Dec. 25, 2003; US2004/0016916 to Bronstad, published Jan. 29,2004; EP 000149567A2 to DuPuis published Jul. 24, 1985; DE003106694A1 toUrberger, published September 1982;

U.S. Pat. No. 4,674,911 to Gertz, issued Jun. 23, 1987, relies on airchambers to supply resiliency to the barrier.

U.S. Pat. No. 4,407,484 to Meinzer, issued Oct. 4, 1983, discloses abarrier system that relies on springs for resiliency and attenuation ofthe vehicle's impact. Various barrier systems use fluid to lessen thevehicle impact. See, for example: U.S. Pat. No. 4,452,431 to Stephens etal., issued Jun. 5, 1984, and U.S. Pat. No. 4,583,716 to Stephens etal., issued Apr. 22, 1986, disclose water filled buffer cartridges thatare restrained with cables in a pivotable diaphragm. Likewise, U.S. Pat.No., 3,672,657 to Young et al., issued Jun. 27, 1972, and U.S. Pat. No.3,674,115 to Young et al, issued Jul. 4, 1972, issued disclose liquidfilled containers arranged in a barrier system; U.S. Pat. No. 3,680,662to Walker et al., issued Aug. 1, 1972, shows clusters of liquid filledbuffers.

Various other systems include reusable energy absorbing devices. Forexample: U.S. Pat. No. 5,112,028 to Laturner, issued May 12, 1992; U.S.Pat. No. 5,314,261 to Stephens, issued May 24, 1994; U.S. Pat. No.6,010,275 to Fitch, issued Jan. 4, 2000; U.S. Pat. No. 6,085,878 toAraki et al., issued Jul. 11, 2000; U.S. Pat. No. 6,149,134 to Banks etal, issued Nov. 21, 2000; U.S. Pat. No. 6,553,495 to Williams et al.,issued Mar. 18, 2003; U.S. Pat. No. 6,554,429 to Stephens et al., issuedApr. 29, 2003; US2003/0210953 A1 to Williams et al., published Nov. 13,2003; JP 356131848A to Miura et al., published Oct. 15, 1981; EP000437313A1 to Guerra, published Jul. 17, 1991.

U.S. Pat. No. 4,237,240 to Jarre et al., issued Dec. 2, 1980, disclosesa flexible polyurethane foam having a high-load bearing capacity and alarge energy absorption capacity upon impact.

U.S. Pat. No. 4,722,946 to Hostettler, issued Feb. 2, 1988, disclosesenergy absorbing polyurethane elastomers and foams. U.S. Pat. No.6,410,609 to Taylor et al., issued Jun. 25, 2002, discloses low pressurepolyurethane foams.

There is a need for an impact attenuator barrier system which minimizesor prevents injury to occupants of a vehicle.

There is a further need for an impact attenuator barrier system vehiclethat is fully recoverable upon impact.

There is a further need for an impact attenuator barrier system that iseconomical, reliable in operation and easy to install and maintain.

There is a further need for an impact attenuator barrier system that isuseful in is various environments, including, for example, publichighways, racetrack, and marine applications including protecting piers.

There is a further need for an impact attenuator barrier system thatwill absorb impact energies from trucks and cars traveling at highspeeds.

There is a further need for an impact attenuator barrier system that,when impacted, does not disintegrate and cause debris to be scatteredaround the site of impact.

SUMMARY OF THE INVENTION

In one aspect, the present invention relates to an impact attenuatorbarrier system for vehicle safety that benefits from theinterrelationship of a number of features: the use of a cast thermosetpolyurethane elastomeric composition in the impact attenuator barriersystem, the method of forming such elastomeric composition using certainprescribed mixing and processing steps, the shape of the elastomericbarrier members, and the assembly of the barrier members into the impactattenuator barrier system.

In another aspect, the present invention relates to an impact attenuatorsystem having side beam assemblies and a nose assembly secured to theside beam assemblies. The side beam assemblies include a plurality ofside panels where adjacent side panels overlap such that the side panelmembers are in a nested linear arrangement. At least one diaphragm panelis positioned between opposing side panels and is secured to theopposing side panels by at least one securing mechanism. The opposingside panels and the diaphragm panels define at least one bay. At leastone hyperelastic member is positioned in the at least one bay. At leastone anchoring system includes at least one cable which secures the sidepanels and diaphragm panels together.

In a specific aspect, the present invention further relates to an impactattenuator system where the hyperelastic member comprises an energyabsorbing material that behaves in a rate-independent hyperelasticmanner such that its permanent set is minimized so that the materialmaintains consistent force-displacement characteristics over a widerange of impact energy while remaining fully recoverable.

In another specific aspect, the present invention further relates to aroadway barrier comprising at least one hyperelastic member. Thehyperelastic member comprises an energy absorbing material that behavesin a rate-independent hyperelastic manner such that its permanent set isminimized so that the energy absorbing material maintains consistentforce-displacement characteristics over a wide range of impactvelocities while remaining fully recoverable.

In yet another specific aspect, the present invention relates to anenergy absorbing hyperelastic material which comprises a mixture ofreactive components comprising an MDI-polyester and/or an MDI-polyetherprepolymer, at least one long-chain polyester and/or polyether polyol,at least one short-chain diol, and at least one catalyst. Thehyperelastic material behaves in a rate-independent hyperelastic mannerand has a permanent set that is minimized so that the hyperelasticmaterial absorbs tremendous amounts of impact energy while remainingfully recoverable when used in energy-absorbing applications. In certainembodiments the reactive components are combined in a proportion thatprovides about 1-10% excess of isocyanate groups in the total mixture.

It is to be understood that the hyperelastic material is especiallysuitable for use in various impact attenuating environments andproducts. As such, it is within the contemplated scope of the presentinvention that a wide variety of other types of products can be madeusing the hyperelastic materials of the present invention. Examples ofsuch products include, but are not limited to, protective gear for workand sports, including helmets and pads, car seats, pedestal seats onhelicopters, bumpers for loading docks, and the like.

In yet another specific aspect, the present invention relates to amethod for making hyperelastic materials which comprising combiningreactive components in certain preferred proportions and providingsufficient processing times such that there is a desired level ofreactivity. The method thereby allows ample pour time and minimizede-mold time during manufacture.

Various objects and advantages of this invention will become apparent tothose skilled in the art from the following detailed description of thepreferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration, in plan view, of one embodiment ofan impact attenuator system.

FIG. 2 is a schematic illustration, in side elevation view, of theembodiment shown in FIG. 1.

FIG. 3 is a schematic illustration, in an end elevational view, as takenalong the line 3-3 in FIG. 2.

FIG. 4 is a schematic illustration, in side elevation, taken along theline 4-4 in FIG. 1.

FIG. 5 is a schematic illustration, in a perspective view, of theembodiment shown in FIG. 1.

FIG. 6 is a schematic illustration, in plan view, of the embodiment ofthe impact attenuator system shown in FIG. 1 in a compressed state.

FIG. 7 is a schematic illustration, in side elevation view, of theembodiment shown in FIG. 2, in a compressed state.

FIG. 8 is a schematic illustration, in plan view, of another embodimentof an impact attenuator system.

FIG. 9 is a schematic illustration, in side elevation view, of theembodiment shown in FIG. 8.

FIG. 10 is a schematic illustration, in an end elevational view, astaken along the line 9-9 in FIG. 8.

FIG. 11 is a schematic illustration, in side elevation, taken along theline 11-11 in FIG. 8.

FIG. 12 is a schematic illustration, in an end elevational view, astaken along the line 12-12 in FIG. 9.

FIG. 13 is a schematic illustration, in plan view, of the embodiment ofthe impact attenuator system shown in FIG. 8 in a compressed state.

FIG. 14 is a schematic illustration, in side elevation view, of theembodiment shown in FIG. 9, in a compressed state.

FIG. 15 is a graph showing the low-strain summary of hyperelasticmechanical properties at 23° C.

FIG. 16 is a graph showing the mid-strain summary of hyperelasticmechanical properties at 23° C.

FIG. 17 is a graph showing the high-strain summary of hyperelasticmechanical properties at 23° C.

FIG. 18 is a graph showing representative stress-strain curves forenergy absorbing materials.

FIG. 19 is a schematic illustration of a cross-sectional view of analternative embodiment of a hyperelastic member useful in the impactattenuator system.

FIG. 20 is a schematic illustration of a cross-sectional view of analternative embodiment of a hyperelastic member useful in the impactattenuator system.

FIG. 21 is a schematic illustration of a cross-sectional view of analternative embodiment of a hyperelastic member useful in the impactattenuator system.

FIG. 22 is a schematic illustration of a cross-sectional view of analternative embodiment of a hyperelastic member useful in the impactattenuator system shown under a compression stressed, yet resilient,state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

In one aspect, the present invention is directed to an impact attenuatorbarrier system, particularly for use in vehicle applications such asracetracks and highways or in protecting piers and the like.

In another aspect, the present invention provides an impact attenuatorsystem which incorporates an array of unique, fully recoverablehyperelastic energy absorbing elements.

In another aspect, the present invention provides a roadway barriercomprising at least one hyperelastic member, wherein the hyperelasticmember comprises an energy absorbing material that behaves in arate-independent hyperelastic manner wherein its permanent set isminimized so that the energy absorbing material maintains consistentforce-displacement characteristics over a wide range of impactvelocities while remaining fully recoverable.

Referring now to FIGS. 1-6, one embodiment of the impact attenuatorsystem 10 is shown. The impact attenuator system 10 includes a firstside beam assembly 12 and an opposing, or second, side beam assembly 14.The first and second beam assemblies 12 and 14 are in opposedrelationship. In the embodiments shown, the first and second beamassemblies 12 and 14 are in opposed and parallel relationship. It is tobe understood, however, that in other embodiments, the beam assembliesdo not need to be parallel. For, example, in certain highwayapplications, it is desired that the beam assemblies have a taperedconfiguration in order to accommodate abutment geometry and/or providestage reaction force from the system (e.g., the rear bays mayincorporate a more narrow array of energy dissipating material while thefront bays incorporate a more narrow array of energy dissipatingmaterial to provide softer response in the early stage of impact and amore still response as the vehicle proceeds further into the system).The first beam assembly 12 has a first, or leading, end 15 and a secondend 16. Likewise, the second beam assembly 14 has a first, or leading,end 17 and a second end 18.

The impact attenuator system 10 also includes a nose assembly 19 that issecured in a suitable manner to the first end 15 of the first beamassembly 12 and to the first end 17 of the second beam assembly 14.

Each side beam assembly 12 and 14 further includes a plurality of sidepanels generally shown here as 20 a, 20 b, 20 c, 20 d and 20 e. For easeof illustration it should be understood that each side beam assembly 12and 14 have similar side panel members where the side panels thatcomprise the side beam assembly 12 are designated as 20 a-20 e and theside panels that comprise the side beam assembly 14 are designated as20′a-20 e′; only one side will be discussed in detail for ease ofexplanation. The first side panel 20 a has a first end 22 a and a secondend 24 a; likewise each subsequent panel 20 b, etc. has first ends 22 b,etc., and second ends 24 b, etc. The second end 24 a overlaps the firstend 22 b of the adjacent panel 20 b. Likewise, each adjacent panel hasoverlapping first and second ends. The side panel members 20 a-20 e arein a nested linear arrangement. The side panel members 20 a′-20 e′ arealso in a nested linear arrangement. Each side panel 20 can have athree-dimensional shape, such as a wave, or corrugated, shape, as shownin FIGS. 3 and 5. It should be understood that the side panels 20 canhave other suitable dimensions, as will become apparent from thefollowing description.

Each side panel 20 generally defines at least one longitudinallyextending opening 26. As best seen in the embodiment shown in FIG. 5,each side panel 20 has an upper longitudinally extending opening, orslot, 26 a and a lower longitudinally extending opening, or slot, 26 bthat are in parallel relationship. The slot 26 a on the side panel 20 aat least partially overlaps the adjacent slot 26 a on the adjacent sidepanel 20 b; likewise, each adjacent side panel has overlapping slots 26.

The impact attenuator system 10 further includes a plurality ofdiaphragm panels generally shown here as 30 a, 30 b, 30 c, 30 d and 30e. For ease of illustration it should be understood that each diaphragmpanel can have the same features, and that only one diaphragm panel willbe discussed in detail for ease of explanation. As best seen in FIG. 3,the each of the diaphragm panel 30 can be comprised of first and secondupright members 32 and 34 and at least one or more cross members,generally shown as 36 a, 36 b, 36 c, 36 d and 36 e, which extend betweenthe first and second upright members 32 and 34. The first and secondupright members include a plurality of spaced apart openings 38. Eachopening 38 can receive a securing mechanism 40. In other embodiments,the diaphragm panel 30 can have other configurations for the crossmembers 36, such as formed into an X shape (not shown) or other suitableconfiguration.

The first diaphragm panel 30 a is positioned between opposing sidepanels 20 a and 20 a′ at substantially a right angle. The firstdiaphragm panel 30 a is secured to the opposing side panels 20 a and 20a′ by one of the securing mechanisms 40. The securing mechanism 40 cancomprise at least one screw-type member 42 that can have a head that iswider than the width of the slot 26; alternatively the securingmechanism 40 can include at least one washer-type member 44 that axiallyfits over the screw-type member 42 such that the washer-type member haslength and width dimensions that are greater than the width of the slot26. The screw-type member 42 extends from the outer surface of the sidepanel 20 through the slot 26, through the adjacent opening 38 in theupright member 32 (or 34) of the diaphragm panel 30, and is held inposition with a suitable locking member 46, such as a hex nut. It is tobe understood that the securing mechanism 40 is capable of beinglongitudinally moved along the slot 26, as will be more fully explainedbelow.

As at least partially assembled, the impact attenuator system 10includes a plurality of opposing side panels 20 a-20 e and 20 a′-20 e′and a plurality of diaphragm panels 30 a-30 e. As assembled, the firstopposing side panels 20 a and 20 a′ are secured to the first diaphragmpanel 30 a. That is, the first upright member 32 of the diaphragm panel30 is secured to the first side panel 20 a and the second upright member24 of the diaphragm panel 30 a is secured to the first opposing sidepanel 20 a′ by having securing mechanisms 40 extend through the slots 26in the side panels 20 and through the adjacent opening 38 in the uprightmember 32 (or 34). Likewise, the remaining side panels are secured tothe remaining diaphragm panels.

The impact attenuator system 10 thus defines a plurality of bays 50 a-50e. Each bay 50 is defined by the opposing side panels 20 and diaphragmpanels 30. As best seen in FIG. 1, the bay 50 a is defined by theopposing side panels 20 a and 20 a′ and by the diaphragm panel 30 a andthe nose assembly 19. Likewise, the remaining bays 50 b-50 e are definedby corresponding side panels and diaphragm panels. It is to beunderstood that the impact attenuator system 10 can include fewer ormore side panels and diaphragm panels, and that the numbers anddimensions of such side panels and diaphragm panels will depend, atleast in part, on the end use and the object which is being protected.

The impact attenuator system 10 includes a plurality, or array, ofhyperelastic members 60. In the embodiment shown, each hyperelasticmember 60 has a substantially tubular or columnar shaped sidewalls 62and at least one interior structural member 64. In the embodiment shown,the structural member 64 generally has an X-shaped cross-section suchthat the structural member 64 defines at least one internal opening 66.It is to be understood that the hyperelastic members 60 can havespecific shapes and dimensions that best meet the end use requirements.For example, in one embodiment, as shown in the figures herein, thehyperelastic members 60 have a generally square pillar conformation andhave an x-shaped structural cross-section 64 which allows eachhyperelastic member 60 to most effectively absorb impact energies, aswill be further explained below. It is to be understood that the shapeof the hyperelastic member 60 can have different configurations. Forexample, FIG. 19 is a schematic illustration of an alternativeembodiment of a hyperelastic member 260 having a plurality of structuralmembers 264 that define alternating large openings 266 and smallopenings 268. The hyperelastic member 260 also defines a plurality ofexternal openings 270 that are spaced along the external surface 272 ofthe structural member 260.

FIG. 20 is a schematic illustration of an alternative embodiment of ahyperelastic member 360 having a plurality of structural members 364that define alternating large openings 366, medium openings 367, andsmall openings 368. The hyperelastic member 360 also defines a pluralityof external openings 370 that are spaced along the external surface 372of the structural member 360.

FIG. 21 is a schematic illustration of an alternative embodiment of ahyperelastic member 460 having a plurality of structural members 464that define alternating triangular openings 466 and diamond shapedopenings 468.

FIG. 22 is a schematic illustration of an alternative embodiment of ahyperelastic member 560 showing the member 560 in a temporarilycompressed state and showing the member in an uncompressed, or relaxedstate, in phantom. The hyperelastic member 560 has a plurality ofstructural members 564 that define triangular openings 566. Thestructural sections 564 at least partially collapse into the openings566 when the hyperelastic member 560 is under compression. Once thecompressive force is removed, the hyperelastic member 560 reverts backto the embodiment 560′ as shown in phantom.

The impact attenuator system 10 further includes first and secondanchoring systems 70 a and 70 b. For ease of illustration it should beunderstood that each anchoring systems 70 a and 70 b can have the samefeatures, and that only one anchoring system 70 will be discussed indetail for ease of explanation. In the embodiment shown, the anchoringsystem 70 includes upper and lower cables 72 and 74 which are secured attheir first ends 71 and 73, respectively, to a first, or front,anchoring mechanism 76 such as a loop or other device. In the embodimentshown, the upper and lower cables 72 and 74 are secured at their secondends 75 and 77, respectively, to second, or rear, anchoring mechanisms80. In other embodiments, the anchoring system 70 can comprise fewer ormore cables. The front anchoring mechanism 76 is securely anchored tothe ground (not shown) in a suitable manner at or below ground level infront of the impact attenuator system 10. As best seen in the embodimentshown in FIG. 4, the lower cable 74 extends through a lower cable guideopening 82 in each of the upright members 32 in each of the diaphragmpanels 30. In the embodiment shown, the lower cable 74 in extends in arearward direction at approximately three inches above ground and isattached to an anchor system (not shown) at cable height in the rear ofthe impact attenuator system 10.

The upper cable 72 extends through an upper cable guide opening 84 ineach of the upright members 32 in each of the diaphragm panels 30. Inthe embodiment shown, the first diaphragm panel 30 a has its upper cableguide opening 84 a at a spaced apart first distance from the lower cableguide opening 82 a; the second diaphragm panel 30 b has its upper cableguide opening 84 b at a spaced apart second distance from the lowercable guide opening 82 b. The first distance is less than the seconddistance such that the upper cable 72 is first guided in an upwarddirection from the front anchoring mechanism 76 and is guided in anupward direction from the first diaphragm panel 30 a to the seconddiaphragm panel 30 b. Thereafter, the upper cable 72 extends from thesecond diaphragm panel 30 b through the diaphragm panels 30 c-30 e in arearward direction that is substantially parallel to the lower cable 74.Both the upper cable 72 and the lower cable 74 are anchored at thesecond anchoring mechanism 80. In the embodiment shown, the portion ofthe upper cable 72 that extends through the diaphragm panels 30 c-30 eis about fifteen inches above ground level.

In an end-on impact where a vehicle first impacts the nose assembly 19,as schematically shown in FIGS. 6 and 7, the impact attenuator system 10deforms by having the sets of nested side panels 20 a-20 a′-20 e-20 e′telescope onto adjacent side panels; that is, the side panels 20 a-20 a′through at least one set of the adjacent side panels 20 b-20 b′ to 20e-20 e′ are moved by the impacting vehicle, allowing the impactattenuator system 10 to deflect in the longitudinal direction. Sinceeach set of side panels 20 a-20 a′-20 e-20 e′ is connected to thecorresponding diaphragm panel 30 a-e by the plurality of individualsecuring mechanisms 40 that are positioned in the corresponding slots26, the first set of side panels 20 a-20 a′ is slidingly moved along theslots 26 in the second set of side panels 20 b-20 b′, and so on. Thedistance the sets of side panels are rearwardly displaced and the numberof set of side panels that are rearwardly displaced depends on theimpact on the impact attenuator system 10. This telescoping feature ofthe impact attenuator system 10 of the present invention is intended tosafely bring to a stop a vehicle that strikes the system 10 on its endand to subsequently return the system 10 to its original position. Thenumber of bays 50, the number of hyperelastic elements 60 per bay, andthe geometry of the hyperelastic elements 60 can be readily modified toaccommodate specific applications of the system 10 depending on expectedrange impact energies. For example, the configuration of hyperelasticelements 60 and the number of bays 50 shown in FIG. 1 will safely stop a3400-lb car impacting at a speed of 50 mph in a head-on impact. Themaximum 10 ms average ridedown acceleration in this case isapproximately 25-30 g's, which is a 70-75% reduction of the impact forcecompared to a frontal impact of the vehicle into a rigid wall at 50 mph.

The impact attenuator system 10 of the present invention also has theability to redirect vehicles that impact on the side of the system 10.To accommodate such side impacts, while not compromising the performanceof the system in end-on impacts, the side panels 20 are preferablycomposed of short sections of overlapping steel or HDPE panels whichdistribute the impact forces between each bay 50 of the system duringside impacts. During impacts on the side of the system 10, the impactforces are distributed from the side panels 20 through the diaphragms 30to the cables 72 and 74, which act in tension to transfer the impactingload to the anchors, thereby allowing the system to safely redirect thevehicle away from the hazard.

Referring now to FIGS. 8-18 another embodiment of an impact attenuatorsystem 110 is shown which can be secured in a different manner. Theimpact attenuator system 110 includes a first side beam assembly 112 andan opposing, or second, side beam assembly 114. The first and secondbeam assemblies 112 and 114 are in parallel and opposed relationship.The first beam assembly 112 has a first, or leading, end 115 and asecond end 116. Likewise, the second beam assembly 114 has a first, orleading, end 117 and a second end 118.

The impact attenuator system 110 also includes a nose assembly 119 thatis secured in a suitable manner to the first end 115 of the first beamassembly 112 and to the first end 117 of the second beam assembly 114.

Each side beam assembly 112 and 114 further includes a plurality of sidepanels generally shown here as 120 a, 120 b, 120 c, 120 d and 120 e. Forease of illustration it should be understood that each side beamassembly 112 and 114 have similar side panel members where the sidepanels that comprise the side beam assembly 112 are designated as 120a-120 e and the side panels that comprise the side beam assembly 114 aredesignated as 120′a-120 e′; only one side will be discussed in detailfor ease of explanation. The first side panel 120 a has a first end 122a and a second end 124 a; likewise each subsequent panel 120 b, etc. hasfirst ends 122 b, etc., and second ends 124 b, etc. The second end 124 aoverlaps the first end 122 b of the adjacent panel 120 b. Likewise, eachadjacent panel has overlapping first and second ends. The side panelmembers 120 a-120 e are in a nested linear arrangement. The side panelmembers 120 a′-120 e′ are also in a nested linear arrangement. Each sidepanel 120 can have a three-dimensional shape, such as a wave, orcorrugated, shape, as shown in FIGS. 10 and 12. It should be understoodthat the side panels 20 can have other suitable dimensions, as willbecome apparent from the following description.

Each side panel 120 generally defines at least one longitudinallyextending opening 126. As best seen in the embodiment shown in FIG. 9,each side panel 120 has an upper longitudinally extending opening, orslot, 126 a and a lower longitudinally extending opening, or slot, 126 bthat are in parallel relationship. The slot 126 a on the side panel 120a at least partially overlaps the adjacent slot 126 a on the adjacentside panel 120 b; likewise, each adjacent side panel has overlappingslots 126.

The impact attenuator system 110 further includes a plurality ofdiaphragm panels generally shown here as 130 a, 130 b, 130 c, 130 d and130 e. In this embodiment, the is last diaphragm panel is designated as130 e. It should be understood, however, that the impact attenuatorsystem 110 can have a different number of diaphragm panels; forconsistency in explanation, the last diaphragm panel will designatedherein as 130 e.

As best seen in FIGS. 8 and 19, the last diaphragm panel 130 e generallyhas a length that is shorter than the forwardly placed diaphragm panels.For ease of illustration it should be understood that each remainingdiaphragm panel 130 a-130 d can have the same features, and that onlyone diaphragm panel will be discussed in detail for ease of explanation.

As best seen in FIG. 10, each of the diaphragm panels 130 can becomprised of first and second upright members 132 and 134 and at leastone or more cross members, generally shown as 136 a, 136 b, 136 c, 136 dand 136 e, which extend between the first and second upright members 132and 134. The first and second upright members include a plurality ofspaced apart openings 138. Each opening 138 can receive a securingmechanism 140. In other embodiments, the diaphragm panel 130 can haveother configurations for the cross members 136, such as formed into an Xshape (not shown) or other suitable configuration.

The first diaphragm panel 130 a is positioned between opposing sidepanels 120 a and 120 a′ at substantially a right angle. The firstdiaphragm panel 130 a is secured to the opposing side panels 120 a and120 a′ by one of the securing mechanisms 140. The securing mechanism 140can comprise at least one screw-type member 142 that can have a headthat is wider than the width of the slot 126; alternatively the securingmechanism 140 can include at least one washer-type member 144 thataxially fits over the screw-type member 142 such that the washer-typemember has length and width dimensions that are greater than the widthof the slot 126. The screw-type member 142 extends from the outersurface of the side panel 120 through the slot 126, through the adjacentopening 138 in the upright member 132 (or 134) of the diaphragm panel130, and is held in position with a suitable locking member 146, such asa hex nut. It is to be understood that the securing mechanism 140 iscapable of being longitudinally moved along the slot 126, as will bemore fully explained below.

As at least partially assembled, the impact attenuator system 110includes a plurality of opposing side panels 120 a-120 e and 120 a′-120e′ and a plurality of diaphragm panels 130 a-130 e. As assembled, thefirst opposing side panels 120 a and 120 a′ are secured to the firstdiaphragm panel 130 a. That is, the first upright member 132 of thediaphragm panel 130 is secured to the first side panel 120 a and thesecond upright member 124 of the diaphragm panel 130 a is secured to thefirst opposing side panel 120 a′ by having securing mechanisms 140extend through the slots 126 in the side panels 120 and through theadjacent opening 138 in the upright member 132 (or 134). Likewise, theremaining side panels are secured to the remaining diaphragm panels.

The impact attenuator system 110 thus defines a plurality of bays 150a-150 e. Each bay 150 is defined by the opposing side panels 120 anddiaphragm panels 130. As best seen in FIG. 8, the bay 150 a is definedby the opposing side panels 120 a and 120 a′ and by the diaphragm panel130 a and the nose assembly 119. Likewise, the remaining bays 150 b-150e are defined by corresponding side panels and diaphragm panels. It isto be understood that the impact attenuator system 110 can include feweror more side panels and diaphragm panels, and that the numbers anddimensions of such side panels and diaphragm panels will depend, atleast in part, on the end use and the object which is being protected.

The impact attenuator system 110 includes a plurality, or array, ofhyperelastic members 160. In the embodiment shown, each hyperelasticmember 160 has a substantially tubular or columnar shaped sidewalls 162and at least one interior structural member 164. In the embodimentshown, the structural member generally has an X-shaped cross-section. Itis to be understood that the hyperelastic members 160 can have specificshapes and dimensions that best meet the end use requirements. Forexample, in one embodiment, as shown in the figures herein, thehyperelastic members 160 have a generally square pillar conformation andhave an x-shaped structural cross-section 164 which allows eachhyperelastic member 160 to most effectively absorb impact energies, aswill be further explained below.

The impact attenuator system 110 further includes first and secondanchoring systems 170 a and 170 b. For ease of illustration it should beunderstood that each anchoring systems 170 a and 170 b can have the samefeatures, and that only one anchoring system 170 will be discussed indetail for ease of explanation. In the embodiment shown, the anchoringsystem 170 includes upper and lower cables 172 and 174 which are securedat their first ends 171 and 173, respectively, to a first, or front,anchoring mechanism 176 such as a loop or other device. In theembodiment shown, the upper and lower cables 172 and 174 are secured attheir second ends 175 and 177, respectively, to a second, or rear,anchoring mechanism 190.

The rear anchoring mechanism 190 includes a pair of spaced apart andparallel support members 192 a and 192 b, such as I-beams. The shorterlast diaphragm panel 130 e is connected to the support members 192 a and192 b by at least one or more suitable connecting means 194 such asmounting brackets. The second end 175 of the upper cable 172 is securedto the support member 192. The second end 177 of the lower cable 174 isalso secured to the support member 192. The rear anchoring mechanism 190further includes a first elbow cable guard 196 a mounted on the first Ibeam support member 192 a and a second elbow cable guard 196 b mountedon the second I beam support member 192 b. The side beam panels 20 arestructural members with sufficient height to shield the interiorcomponents of the system from direct impact from a vehicle and provideadequate strength to transfer load to the diaphragms 30 when impacted atany point on the face of the panels. The materials that the panels maybe constructed from include, but are not limited to, High DensityPolyethylene, steel, aluminum, plastic, fiber reinforced plastic andvarious composite materials. In certain embodiments, it is preferredthat the material be recoverable, or semi-recoverable, produce no, orvery little, debris when impacted by a vehicle, and can withstandmultiple vehicle impacts before needing to be replaced. In theembodiment shown, the side panels are made from corrugated sheet steel(e.g., 10-gauge thrie-beam).

It is to be understood that, in other embodiments, the anchoring system170 can comprise fewer or more cables. The front anchoring mechanism 176is securely anchored to the ground (not shown) in a suitable manner ator below ground level in front of the impact attenuator system 10. Asbest seen in the embodiment shown in FIG. 11, the lower cable 174extends through a lower cable guide opening 178 in each of the uprightmembers 132 in each of the diaphragm panels 130. In the embodimentshown, the lower cable 174 in extends in a rearward direction atapproximately three inches above ground and is attached to an anchorsystem (not shown) at cable height in the rear of the impact attenuatorsystem 110.

The upper cable 172 extends through an upper cable guide opening 184 ineach of the upright members 132 in each of the diaphragm panels 130. Inthe embodiment shown, the first diaphragm panel 130 a has its uppercable guide opening 184 a at a spaced apart first distance from thelower cable guide opening 182 a; the second diaphragm panel 130 b hasits upper cable guide opening 184 b at a spaced apart second distancefrom the lower cable guide opening 182 b. The first distance is lessthan the second distance such that the upper cable 172 is first guidedin an upward direction from the front anchoring mechanism 176 and isguided in an upward direction from the first diaphragm panel 130 a tothe second diaphragm panel 130 b. Thereafter, the upper cable 172extends from the second diaphragm panel 130 b through the diaphragmpanels 130 c-130 e in a rearward direction that is substantiallyparallel to the lower cable 174. Both the upper cable 172 and the lowercable 174 are anchored at the second anchoring mechanism 190. In theembodiment shown, the portion of the upper cable 172 that extendsthrough the diaphragm panels 130 c-130 e is about fifteen inches aboveground level.

In an end-on impact where a vehicle first impacts the nose assembly 119,as schematically shown in FIGS. 12-14, the impact attenuator system 110deforms by having the sets of nested side panels 120 a-120 a′-120 e-120e′ telescope onto adjacent side panels; that is, the side panels 120a-120 a′ through at least one set of the adjacent side panels 120 b-120b′ to 120 e-120 e′ are moved by the impacting vehicle, allowing theimpact attenuator system 110 to deflect in the longitudinal direction.Since each set of side panels 120 a-120 a′-120 e-120 e′ is connected tothe corresponding diaphragm panel 130 a-e by the plurality of individualsecuring mechanisms 140 that are positioned in the corresponding slots126, the first set of side panels 120 a-120 a′ is slidingly moved alongthe slots 126 in the second set of side panels 120 b-120 b′, and so on.The distance the sets of side panels are rearwardly displaced and thenumber of set of side panels that are rearwardly displaced depends onthe impact on the impact attenuator system 110.

This telescoping feature of the impact attenuator system 110 of thepresent invention is intended to safely bring to a stop a vehicle thatstrikes the system 110 on its end and to subsequently return the system110 to its original position. The number of bays 150, the number ofhyperelastic elements 160 per bay, and the geometry of the hyperelasticelements 160 can be readily modified to accommodate specificapplications of the system 110 depending on expected range impactenergies. For example, the configuration of hyperelastic elements 160and the number of bays 150 shown in FIG. 8 will safely stop a 3400-lbcar impacting at a speed of 50 mph in a head-on impact. The maximum 10ms average ridedown acceleration in this case is approximately 25-30g's, which is a 70-75% reduction of the impact force compared to afrontal impact of the vehicle into a rigid wall at 50 mph.

The impact attenuator system 110 of the present invention also has theability to redirect vehicles that impact on the side of the system 110.To accommodate such side impacts, while not compromising the performanceof the system in end-on impacts, the side panels 120 are preferablycomposed of short sections of overlapping steel or HDPE panels whichdistribute the impact forces between each bay 150 of the system duringside impacts. During impacts on the side of the system 110, the impactforces are distributed from the side panels 120 through the diaphragms130 to the cables 172 and 174, which act in tension to transfer theimpacting load to the anchors, thereby allowing the system to safelyredirect the vehicle away from the hazard.

In certain embodiments the side beam assemblies form a rigid U-shapedstructure which preferably is made of a composite material, includingfor example, metals such as steel, and plastics such as high densitypolyethylene. The composite material is recoverable, orsemi-recoverable, produces no, or very little, debris when impacted by avehicle, and can withstand multiple vehicle impacts before needing to bereplaced. The hyperelastic elements crush in the direction of impactwhich is the primary energy dissipating mechanism. Because of thegeometry of the hyperelastic elements shown in the current embodiment,the hyperelastic elements also spread outward as they crush.

In another aspect, the invention is directed to a composition andprocess for forming hyperelastic elements.

The hyperelastic material used herein is a novel energy absorbingmaterial that behaves in a rate-independent hyperelastic manner. Thehyperelastic material behaves in a manner such that its permanent set isminimized so that the energy absorbing material maintains consistentforce-displacement characteristics over a wide range of impactvelocities while remaining fully recoverable.

The hyperelastic material behaves in a hyperelastic manner under dynamicloadings of high strain rates of up to at least about 900-1000s⁻¹. Thehyperelastic material uniquely allows for direct impacts and also allowsfor the instantaneous recovery of the components from which the materialis made. The hyperelastic material has non-linear elastic responses inenergy absorbing applications.

It is to be understood that the hyperelastic material is especiallysuitable for use in various impact attenuating environments andproducts. As such, it is within the contemplated scope of the presentinvention that a wide variety of other types of products can be madeusing the hyperelastic materials of the present invention. Examples ofsuch products include, but are not limited to, protective gear for workand sports, including helmets and pads, car seats, pedestal seats onhelicopters, bumpers for loading docks, and the like.

It is to be understood that elastomers belong to a specific class ofpolymeric materials where their uniqueness is their ability to deform toat least twice their original length under load and then to return tonear their original configuration upon removal of the load. Elastomersare isotropic, nearly incompressible materials which behave as linearelastic solids under low strains and low strain rates. As thesematerials are subjected to larger strains under quasistatic loading,they behave in a non-liner manner. This unique mechanical behavior iscalled hyperelasticity. Hyperelastic material have the ability to dowork by absorbing kinetic energy transferred from impact through anelastic deformation with little viscous damping, heat dissipation (fromfriction forces) or permanent deformation (i.e., permanent set). Thismechanical energy can then be returned nearly 100% allowing thecomponents to return to their original configuration prior to impactwith negligible strain.

Unfortunately, an added complexity to elastomers is their strain rateand strain history dependence under dynamic loading, which is calledviscoelasticity. The viscoelastic nature of elastomers causes problemsresulting in hysteresis, relaxation, creep and permanent set. Permanentset is when elastomers undergo a permanent deformation where thematerial does not return to zero strain at zero stress. This deformationhowever, tends to stabilize upon repeated straining to the same fixedstrain. To further add to the complexity of the mechanical behavior ofelastomers is the visco-hyperelastic response at high strain underdynamic loading, which is difficult to characterize and test. Oftenstress-strain data from several modes of simple deformation (i.e.,tension, compression and shear) are required as input to materialmodels, which predict their performance.

Thus, in one aspect, the present invention uses hyperelastic materialsthat absorb great amounts of mechanical energy while maintaining fullrecoverability. Traditionally, the viscous component of rubbersdominates under dynamic loading; whereby the strain rate dependence isaccounted for by visco-hyperelastic models, where the static response isrepresented by a hyperelastic model (based on elastic strain energypotential) in parallel with a Maxwell model which takes into accountstrain rate and strain history dependent viscoelasticity.

In yet another specific aspect, the present invention relates to anenergy absorbing hyperelastic material which comprises a mixture ofreactive components comprising an MDI-polyester and/or an MDI-polyetherprepolymer, at least one long-chain polyester and/or polyether polyol,at least one short-chain diol, and at least one catalyst. Thehyperelastic material behaves in a rate-independent hyperelastic mannerand has a permanent set that is minimized so that the hyperelasticmaterial absorbs tremendous amounts of impact energy while remainingfully recoverable when used in energy-absorbing applications. In certainembodiments the reactive components are combined in a proportion thatprovides about 1-10% excess of isocyanate groups in the total mixture.

Polyurethane elastomers are a class of materials known to possesshyperelastic behavior. Of particular interest to the current inventionare polyurethane cast elastomer systems comprised of an isocyanatecomponent, typically methylene diphenyl diisocyanate (MDI), a long chainpolyol comprised of a 1000-2000 MW polyester- or polyether-basedhydroxyl-terminated polyol, and a short chain glycol (e.g.,1,4-butanediol). Such systems are generally mixed with a slight excessof isocyanate groups which are available to undergo further reactionduring the cure and postcure cycle. These reactions result in a fullycured polymer system which is slightly crosslinked and thus exhibits ahigh degree of recoverability subsequent to deformation. Withappropriate choice of components, proper and unique material propertiesand impact response can be achieved which make these polymer materialssuitable for hyperelastic elements in the impact attenuator barriersystem described in the current invention. The preferred hyperelasticmaterial has the following characteristics: Shore A hardness values ofabout 90, Maximum tensile stress ranging from about 4000 to about 7000psi, Elongation at break ranging from about 500 to about 700%, andYoung's modulus ranging from about 4000 to about 6000 psi.

The hyperelastic elements can be formed by combining a full MDIprepolymer system containing a long-chain polyester and/or polyetherpolyol, which requires addition of a short chain glycol as a curative,and a catalyst using a standard mixing/metering machine. The full MDIprepolymer typically has a low % NCO, ranging from between about 5 to10% free isocyanate groups.

Alternatively, the hyperelastic elements can be formed by combining aquasi MDI prepolymer system containing a long-chain polyester and/orpolyether polyol, with both a short chain glycol and a long chainpolyester and/or polyether polyol. Suitable polyester polyols caninclude, without limitation, polyglycol adipates, such asethylene/butylene adipate, or polycaprolactones. Suitable polyetherpolyols can include, without limitation, polypropylene glycol,polyethylene glycol, or combinations thereof.

The quasi MDI prepolymer typically has a higher % NCO, ranging frombetween about 10 to 25% free isocyanate groups. The quasi MDI prepolymertherefore can be cured with a short chain glycol with addition, asnecessary, of a long chain polyol component, in order to achieve thedesired material stiffness and response at the impact condition.

The composition of the hyperelastic elements, when used as a componentin the impact attenuator barrier system described herein, producesdesired G-force reduction and recoverability in actual impact tests. Theprepolymer can be an MDI-polyester and/or polyether prepolymer having afree isocyanate content of about 5 to 25%, and preferably about 19%.Suitable polyesters that can be used with the MDI isocyanate componentinclude, without limitation, polyglycol adipates, such asethylene/butylene adipate, or polycaprolactones. Suitable polyethersthat can be used with the MDI isocyanate component can include, withoutlimitation, polypropylene glycol, polyethylene glycol, or combinationsthereof. The polyol can have an OH# of about 25 to 115, preferably about35 to 80, and most preferably about 56. The short-chain diol caninclude, without limitation, 1,4-butanediol, and can account for about10 to 20% by weight, preferably about 18% by weight of the totalhydroxyl-containing components of the mixture.

Reactive components can be combined in a proportion that provides about1 to 10%, preferably 5% excess of isocyanate groups in the totalmixture. A catalyst package can be utilized which facilitates thechemical reaction of the components and allows demolding of the partswithin a reasonable time frame. The gel time or work life of the systemshould not be shorter than the mold filling time to ensure uniformmaterial properties throughout all sections of the part. The catalystsystem can contain a blend of a tertiary amine catalyst and a tin-basedcatalyst. About a 1:1 to 10:1 weight ratio, preferably about a 4:1weight ratio, of the amine component to the tin component will providedesirable processing characteristics. A total catalyst loading isperformed such that the mold is filled entirely before the materialbegins gelling. This level of reactivity allows ample pour time andminimizes de-mold time during manufacture. In certain embodiments, thechemical reactivity can be adjusted by changing the amount of catalystin the system.

The present invention also is directed to a process for manufacturingthe hyperelastic elements. The process includes heating the componentsto process temperatures, degassing components to remove any dissolved orentrained gases, precisely metering components to a mix chamber,dynamically mixing the components, and dispensing mixed material into amold from which the cured part is subsequently demolded and subjected toan appropriate post cure cycle. Due to differences in component meltpoints and viscosity, appropriate component temperatures, as well asmold temperatures, may range from approximately 100° F. to 250° F.

It should be understood that the examples and embodiments describedherein are for illustrative purposes only and that various modificationsor changes in light thereof will be suggested to persons skilled in theart and are to be included within the spirit and purview of thisapplication.

EXAMPLE 1 Testing of the Hyperelastic Elements

A material for thermoset, cast polyurethane components for use in makingthe hyperelastic elements in the impact attenuator system wasformulated. The material had a Young's modulus of at least about 4000 toabout 6000 psi and provided optimized tensile and elongation propertiesat this stiffness. Samples were prepared from a formulation having thefollowing physical properties: Young's modulus: 5933 psi; Tensilestrength: 6830 psi; and Elongation: 638%.

The samples were submitted for hyper-elastic testing. As seen in theFIGS. 15, 16 and 17, the test results proved satisfactory. FIG. 15 is agraph showing the low-strain summary of hyperelastic mechanicalproperties at 23 C. FIG. 16 is a graph showing the mid-strain summary ofhyperelastic mechanical properties at 23 C. FIG. 17 is a graph showingthe high-strain summary of hyperelastic mechanical properties at 23 C.

Further large scale testing of an impact system incorporating theelements showed desirable properties where the polyurethane wallelements showed high levels of G-force reduction and recoverability ofthe polyurethane elements.

Large-scale testing of an energy absorption system incorporating thesehyperelastic elements showed desirable high level of G-force reductionand recoverability of the polyurethane elements during testing.

The mechanical performance of the material in these large-scale tests isshown in FIG. 18, which represents the typical stress-strain behavior ofthe novel energy absorbing material. It should be noted that thismaterial can display moderate strain rate dependence below 10 s⁻¹, butit is desired that for use in an impact attenuator system, the materialis desired to have minimal strain rate dependence up to 900 to about1000 s⁻¹.

The hyperelastic materials having the specifications described hereinhave not been in existence before this invention thereof. Further, thehyperelastic material displays these unique performance criteria andconstraints given the high kinetic energies, strains and strain ratesinvolved.

EXAMPLE 2 Composition of the Hyperelastic Material

The hyperelastic material of the present invention was prepared using anMDI-polyester prepolymer having a free isocyanate content ofapproximately 19%. A separate long chain polyester component based onethylene/butylene adipate was utilized. The polyol had an OH# ofapproximately 56. The short-chain diol utilized was 1,4-butanediol andaccounted for approximately 18% by weight of the totalhydroxyl-containing components of the mixture.

Reactive components were combined in a proportion that providedapproximately 5% excess of isocyanate groups in the total mixture. Acatalyst package was utilized which facilitated the chemical reaction ofthe components and allowed demold of the parts within a reasonable timeframe. The gel time or work life of the system should not be shorterthan the mold filling time to ensure uniform material propertiesthroughout all sections of the part. The catalyst system contained ablend of a tertiary amine catalyst and a tin-based catalyst. A 4:1weight ratio of the amine component to the tin component provideddesirable processing characteristics. A total catalyst loading of 0.026%by weight was used to provide a gel time of approximately 2.25-2.50minutes.

This level of reactivity allowed ample pour time and minimized de-moldtime during manufacture.

EXAMPLE 3 Process for Making Hyperelastic Material

A three component liquid casting machine equipped with a precision gearpump to accurately meter components and a dynamic mix head to obtainadequate mix quality and heating capability were used. The prepolymer,polyol and short-chain diol reactive components were charged intoholding tanks heated to approximately 110° F. Approximate amounts of thecatalyst components were added to the tank containing the short chaindiol and mixed thoroughly. All components were then degassed under aminimum vacuum of 28 inches Hg until all dissolved gasses were removed.A dry nitrogen pad was then applied to each tank to protect componentsfrom moisture exposure. Pad pressure must be adequate to ensure materialfeed to a suction side of a metering pump. Each pump was calibrated toensure delivery of an appropriate amount of the respective component tothe mix chamber. The total material throughput was approximately 16.5pounds per minute. A mold was heated to an approximate range of 190° F.to 210° F. prior to dispensing mixed material into the cavity. The moldtemperature was maintained at about 200° F. after pouring to ensureproper cure of the material prior to demolding the part. The part wasdemolded in approximately 20 minutes and subsequently post-cured attemperatures between about 200° F. to 250° F. for approximately 12 to 36hours to ensure completion of the chemical reaction and attainment ofmaterial properties. The part was then aged a minimum of 21 days atambient conditions prior to being placed into service as a racetracksafety barrier.

In accordance with the provisions of the patent statutes, the principleand mode of operation of this invention have been explained andillustrated in its preferred embodiment. However, it must be understoodthat this invention may be practiced otherwise than as specificallyexplained and illustrated without departing from its spirit or scope.

1. An impact attenuator system comprises: at least one first side beamassembly and at least one opposing, or second, side beam assembly, thefirst and second beam assemblies are in opposed relationship, the firstbeam assembly having a first, or leading, end and a second end, and thesecond beam assembly having a first, or leading, end and a second end;at least one nose assembly that is secured to the first end of the firstbeam assembly and to the first end of the second beam assembly; eachside beam assembly further including a plurality of side panels, eachside panel having a first end and a second end, wherein the second endof a first panel overlaps the first end of the adjacent panel wherebythe side panel members are in a nested linear arrangement; each sidepanel defining at least one longitudinally extending opening whereinadjacent slots on adjacent side panels at least partially overlap; atleast one diaphragm panel, wherein the diaphragm panel is positionedbetween opposing side panels and is secured to the opposing side panelsby at least one securing mechanism, wherein the securing mechanismextends from an outer surface of the side panel through the slot, thesecuring mechanism being capable of being longitudinally moved along theslot; at least one bay defined by the opposing side panels and thediaphragm panels; at least one hyperelastic member positioned in the atleast one bay; and, at least one anchoring system including at least onecable which is secured at a first end to a first anchoring mechanism andis secured at a second end to a second anchoring mechanism.
 2. Theimpact attenuator system of claim 1, wherein the hyperelastic membercomprises an energy absorbing material that behaves in arate-independent hyperelastic manner whereby its permanent set isminimized so that the energy absorbing material can absorb impact energywhile remaining fully recoverable.
 3. The impact attenuator system ofclaim 1, wherein the hyperelastic member comprises at least one energyabsorbing material has at least the properties of: a Shore A hardnessvalue of at least about 90, elongation at break ranging from about 500to about 700%, and Young's modulus ranging from about 4000 to about 6000psi; and at least withstands: strain rates of up to at least about900-1000s⁻¹, and tensile stresses ranging from at least about 4000 to atleast about 7000 psi.
 4. The impact attenuator system of claim 3,wherein the hyperelastic material behaves in a hyperelastic manner underdynamic loadings of high strain rates of up to at least about900-1000s⁻¹ and has non-linear elastic responses in energy absorbingapplications.
 5. The impact attenuator system of claim 3, wherein thehyperelastic material comprises a thermoset cast polyurethane systemmaterial.
 6. The impact attenuator system of claim 5, wherein thehyperelastic material comprises a polyurethane elastomer.
 7. The impactattenuator system of claim 4, wherein the hyperelastic materialcomprises an energy absorbing hyperelastic material, comprising: amixture of reactive components comprising an MDI-polyester and/or anMDI-polyether prepolymer, at least one long-chain polyester and/orpolyether polyol, at least one short-chain diol, and at least onecatalyst, the hyperelastic material behaving in a rate-independenthyperelastic manner and having a permanent set that is minimized so thatthe hyperelastic material absorbs tremendous amounts of impact energywhile remaining fully recoverable when used in energy-absorbingapplications, wherein the reactive components are combined in aproportion that provides about 1-10% excess of isocyanate groups in thetotal mixture.
 8. The impact attenuator system of claim 7, wherein thehyperelastic material behaves in a hyperelastic manner under dynamicloadings of high strain rates of up to at least about 900-1000s⁻¹ andhas non-linear elastic responses in energy absorbing applications. 9.The impact attenuator system of claim 7, wherein the polyester componentis selected from the group consisting of polyglycol adipates andpolycaprolactones, and wherein the polyether component is selected fromthe group consisting of polypropylene glycol, polyethylene glycol andcombinations thereof.
 10. The impact attenuator system of claim 7,wherein the reactive components are combined in a proportion thatprovides about 5% excess of isocyanate groups in the total mixture. 11.The impact attenuator system of claim 7, wherein the catalyst contains ablend of a tertiary amine catalyst and a tin-based catalyst.
 12. Theimpact attenuator system of claim 11, wherein the tertiary aminecatalyst and said tin-based catalyst is in a ratio of about 4:1.
 13. Theimpact attenuator system of claim 7, wherein a total catalyst loading ofabout 0.026% by weight is used to provide a gel time of about 2.25 to2.50 minutes.
 14. The impact attenuator system of claim 7, wherein thehyperelastic material comprises: a mixture of an MDI-ester prepolymerhaving a free isocyanate content of approximately 19%, at least onelong-chain polyester polyol comprised of ethylene/butylene adipate diolwith an OH# of approximately 56, at least one short-chain diol comprisedof 1,4 butanediol that accounts for approximately 18% by weight of thetotal hydroxyl-containing components of the mixture, and at least onecatalyst comprised of a tertiary amine catalyst and a tin-based catalystin a ratio of about 4:1, wherein a total catalyst loading of about0.026% by weight is used to provide a gel time of about 2.25 to 2.50minutes, wherein the reactive components are combined in a proportionthat provides about 5% excess of isocyanate groups in the total mixture,and wherein the hyperelastic material behaves in a rate-independenthyperelastic manner and has a permanent set that is minimized so that itabsorbs tremendous amounts of impact energy while remaining fullyrecoverable when used in an impact attenuator system.
 15. The impactattenuator system of claim 1, wherein the hyperelastic member hassubstantially tubular or columnar shaped sidewalls and at least oneinterior structural member. 16-63. (canceled)